You can do this with a custom model manager and override the get_queryset function to always filter canceled=False.
class CustomManager(models.Manager):
def get_queryset(self):
return super().get_queryset().filter(canceled=False)
class MyModel(models.Model):
# Blah blah
objects = CustomManager()
Then when calling MyModel.objects.all() it will always exclude canceled objects. Here is a blog post I found helpful on the subject. http://www.b-list.org/weblog/2006/aug/18/django-tips-using-properties-models-and-managers/
EDIT:
Perhaps a better approach with a custom manager would be to attach it to another property, other than objects, such as:
class MyModel(models.Model):
# Blah blah
active = CustomManager()
And in your views your queries would look like MyModel.active.all().
EDIT2:
Updated method spelling from get_query_set to get_queryset for modern versions of django.